Microstructural evolution and mechanical properties of Mg-9.8Gd-2.7Y-0.4Zr alloy produced by repetitive upsetting

Zhou, Hao; Ning, Huiyan; Ma, Xiaolong; Yin, Dongdi; Xiao, Lirong; Sha, Xuechao; Yu, Yandong; Wang, Q.D.; Li, Y.S.

doi:10.1016/j.jmst.2018.01.009

Cited by 46 publications

(11 citation statements)

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“…This material preparation method often requires a complex composition and high costs. Furthermore, alloying may also have a negative effect on its mechanical properties as well as its formability [12][13][14][15][16]. Therefore, surface treatment has so far been one of the most effective and convenient ways for improving corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

et al. 2019

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The formation process of LDHs (layered double hydroxides) coating on magnesium alloy by the CO2 pressurization method was studied. The micro-structure was observed by OM, SEM and GAXRD. The weighted gain curve, apparent activation energy, and CO2 solubility curve were all calculated by equations. The potentiodynamic polarization curve, hydrogen evolution data, and immersion were analyzed by an electrochemical method. The results show that the LDHs coating was formed layer-by-layer. The formation positions were initially on the α-Mg phase, and then on the β-Mg17Al12 phase. It was found to be the most compact after 30 min. The LDHs coating began to appear to have severe cracks and holes over time. The formation process of the LDHs coating can be divided into three stages: a rapid growth stage (0–10 min), slow growth stage (10–20 min), and periodic growth stage (30 min, 1 h). The apparent activation energies in each of the three stages are 21.78, 31.86 and 34.92 kJ mol−1, respectively. The LDHs coating has a compact micro-structure and better anti-corrosion at a pressure of 3 MPa, a temperature of 50 °C and a time of 30 min. The CO2 pressurization promotes a formation reaction rate and achieves a high formation efficiency and good formation stability under the condition of zero pollution.

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Section: Introductionmentioning

confidence: 99%

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

et al. 2019

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“…Conventional ECAP process however has typical drawbacks of reinserting billets into the die for every pass, resulting in inconsistencies in temperature applied for each pass [16][17][18]. Some researchers have therefore resorted to the development of novel processes with higher production efficiency, such as repetitive upsetting (RU) [19][20][21] and rotary die equal channel angular pressing (RD-ECAP) [22][23][24]. Also, another effective plastic deformation in use is the rolling technique.…”

Section: Introductionmentioning

confidence: 99%

Development of a High Strength Mg-9Li Alloy via Multi-Pass ECAP and Post-Rolling

Klu

Song

et al. 2019

Metals

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In this study, a high-strength Mg-9Li alloy was developed via multi-pass equal-channel-angular-pressing (ECAP) and post rolling, of which the yield tensile stress (YTS) and ultimate tensile stress (UTS) were 166 MPa and 174 MPa representing about 219% and 70% increase in YTS and UTS respectively, compared to the cast alloy. The cast alloy was ECAP processed at 200 °C for 4, 8, and 16 passes, followed by room-temperature rolling to a total thickness reduction of 50%. The 8-passes ECAPed (E8) alloy presented the best strength of all the ECAPed alloys, and the post rolling endowed the alloy (E8R) further strengthening and the best strength of all the alloys. Grain-boundary strengthening and dislocation strengthening were the two major factors for the high strength of the processed alloys. The α-Mg phase grains were greatly refined to about 2 μm after 8-passes ECAP, and was further refined to about 800 nm ~1.5 μm after rolling. Significant grain refinement endowed the alloy with sufficient grain-boundary strengthening. Profuse intragranular dislocation accumulated in the deformed matrix, leading to the significant dislocation hardening of the alloy. Rolling-induced strong basal texture of the α-Mg phase also enhanced the further strengthening of the E8R alloy.

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“…As the lightest metallic material, magnesium and its alloys are attracted by aeronautical, automotive, chemical, and medical industries [1,2,3,4,5]. In recent years, wrought magnesium alloys have been well developed due to their remarkable interfacial strengthening induced by high density of grain boundaries and twin boundaries [6,7,8]. Due to the hexagonal close packed (HCP) crystal structure, the number of easy-glide systems in Mg alloys are not enough to satisfy the uniform plastic deformation according to the Von Mises criteria.…”

Section: Introductionmentioning

confidence: 99%

Effect of Micro-Steps on Twinning and Interfacial Segregation in Mg-Ag Alloy

et al. 2019

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Twinning structures and their interfacial segregation play a key role in strengthening of magnesium alloys. Micro-steps are frequently existed in the incoherent twin boundaries, while the effect of them on interface and interfacial segregation is still not clear. In this work, we performed an atomic-scale microstructure analysis using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) to explore the effect of micro-steps on twin and its interfacial segregation in Mg-Ag alloy. Diffraction pattern of the incoherent {10 1 ¯ 1} twin shows that the misorientation has a slight tilt of 5° from its theoretical angle of 125° due to the accumulated effects of the micro-steps and their misfit dislocations in twin boundaries. Most of the micro-steps in {10 1 ¯ 1} twin boundary are in the height of 2 d ( 10 1 ¯ 1 ) and 4 d ( 10 1 ¯ 1 ) , respectively, and both of them have two types according to whether there are dislocations on the micro-steps. The twin boundary is interrupted by many micro-steps, which leads to a step-line distributed interfacial segregation. Moreover, the Ag tends to segregate to dislocation cores, which results in the interruption of interfacial segregation at the micro-steps with dislocations.

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Microstructural evolution and mechanical properties of Mg-9.8Gd-2.7Y-0.4Zr alloy produced by repetitive upsetting

Cited by 46 publications

References 50 publications

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

Formation Process of an LDHs Coating on Magnesium Alloy by a CO2 Pressurization Method

Development of a High Strength Mg-9Li Alloy via Multi-Pass ECAP and Post-Rolling

Effect of Micro-Steps on Twinning and Interfacial Segregation in Mg-Ag Alloy

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